Tuesday, October 19, 2010

A NEW SOURCE OF WYOMING GEMSTONES (Iolite, Ruby, Sapphire, Kyanite)


Group of faceted ruby, pink sapphire &
iolite, Laramie Range, WY
Field reconnaissance in the central Laramie Range of southeastern Wyoming led to the discovery of gem-quality iolite and near-gem cordierite hosted by quartzofeldspathic gneiss, and gem corundum (ruby and sapphire) and kyanite in vermiculite schist and gem kyanite in chlorite-biotite schist and in mica-kyanite gneiss (Hausel, 2002). Prior to this discovery, iolite was unknown in Wyoming other than one obscure reference made by John Sinkankas about an extensive iolite deposit, but provided no location and no description. 

This iolite-ruby-sapphire-kyanite deposit at Palmer Canyon was a major discovery for the State of Wyoming. Not that it was a large deposit, but it proved Wyoming had more to offer. Wyoming, which was only known only for jade, coal and oil and gas, was now considered a unique geological terrain with a variety of rock types, minerals and gemstones. And during a marvelous three decade Era (1977 to 2007) hundreds and hundreds of colored gemstones, diamonds, diamond indicator minerals, kimberlite pipes, lamprophyres, crypto-volcanic structures, minerals and gold anomalies were found. These discoveries along with detailed geological mapping of many complex metamorphic terrains in various mountain ranges and previously ignored mining districts attracted hundreds of prospectors, dozens of mining companies, and $millions of exploration dollars to the Cowboy State. With renewed interest in the State's geology, and the mining and recovery of coal, trona, oil and gas, Wyoming was sitting in a boom era - even when the rest of the country slipped into periodic recession. Nothing had ever occurred like this before in the history of Wyoming and nothing like it has occurred since. It was a golden Era of discovery.   

After the discovery of iolite at Palmer Canyon in the central Laramie Mountains, more iolite gem discoveries were made. These included deposits at Grizzly Creek in 2004 and Sherman Mountains in 2005 as well as gem ruby and sapphire deposits elsewhere in Wyoming. The work also indicated that the geology and metamorphic environment in the central Laramie Mountains was very favorable for gemstones. Previously, cordierite had been reported at Owen Creek by Snyder and others, 1995 with no mention of gemstones. During investigations of this occurrence, the author (Hausel) identified gem iolite and sapphire in 1996. 

The geology and metamorphic grade of the central Laramie Range is suitable for a number of alumina-gems (aluminum-oxides and aluminum silicates). Exploration of anorthosites, syenites, metapelites and vermiculites in this region will undoubtedly lead to many additional discoveries sometime in the future, when the State of Wyoming again finds another prospecting genius. All of these deposits were sitting awaiting for someone to discover them, and it took one individual to actually get out and look.  

The first iolites (0.36 to 1.33 carats) & sapphires
(1.15 to 1.47 carats) faceted from Palmer Canyon
cordierite & corundum recovered by the author.
Photo by Maha Tannous (courtesy of GIA).
The gem-bearing gneisses and schists occur near the margin of the Elmers Rock greenstone belt, an Archean synformal belt of amphibolite-grade metasedimentary and metavolcanic rock within the Wyoming Province (Graff and others, 1982). The Wyoming Province represents an Archean (>2.5 billion year old) basement complex, which underlies much of Wyoming and large portions of Montana (Hausel, Edwards, and Graff, 1991).

Several other gem and semiprecious mineral occurrences have also been identified in Wyoming (Hausel and Sutherland 2000; Hausel, 2014). These include aquamarine, chrome diopside, diamond, jade, labradorite, olivine (peridot), opal, pyrope garnet, variscite, and many unique agates and jaspers. The geology, geochemistry and metamorphic grade in the central Laramie Range are very favorable for crystallization of gem iolite, ruby, kyanite and possibly other gemstones such as sillimanite, andalusite,  staurolite and spectrolite (labradorite). And this doesn't even consider the diamond potential of the area. In the central Laramie Mountains, Hausel and others (2003) identified and mapped a large group of kimberlites at Iron Mountain and nearby Sheep Rock (Hausel and others, 1981). This area also is filled with many unexplained kimberlitic indicator mineral anomalies and the recent reported (unconfirmed) diamond finds by prospectors.

Location

The cordierite and corundum occurrence is in Palmer Canyon along the eastern flank of the central Laramie Range of southeastern Wyoming. Palmer Canyon lies about 16 miles west of Wheatland, a farming community with a population of about 3,500. This community is located along the northern edge of the Denver Basin nearly 70 miles north of Cheyenne. At an elevation of 4,730 feet above sea level, Wheatland has a comparatively mild climate. Recorded temperatures range from a low of 0°F to a high of 105°F. The Palmer Canyon occurrence is located at 5,760 feet above sea level, and nearby peaks reach heights of 6,000 to 7,700 feet, with the highest peak in the Laramie Range (Laramie Peak) located 10 miles to the north at an elevation of 10,019 feet.

Location map of Palmer Canyon
The mineral occurrence is accessible by driving west from Wheatland on the Palmer Canyon road, which is paved from Wheatland to within 0.8 mile of the deposit. The ownership of the deposit is split, such that the surface is private and the minerals are reserved to the Federal government (Vic Norris, personal com, 2001). Claims were filed for gemstones on the mineral estate a few years after the author made the discovery. Thus permission to collect may be necessary from the claimant.

Nearby Occurrences
In addition to Palmer Canyon, several other interesting occurrences are found in this region (Hausel and Jacobson, 2001). The largest group of diamondiferous kimberlites in the United States, which form the State Line district, are 80 miles to the south (Hausel, 1998). Approximately 130,000 gem- and industrial-quality diamonds were recovered from this district. Thirty miles south is the second largest kimberlite district in the United States, known as the Iron Mountain district (Hausel and others, 2000), which remains relatively unexplored for gemstones, even though the kimberlites appear to be favorable hosts for diamond. Twenty miles south, some labradorite feldspar with excellent fire is found within the Laramie Range anorthositic batholith (1.5 billion years old). One can even find this gemstone in the road bed material along Albany County 11 and 12 (Norma Beers, personal communication).

Blue, transparent, barite from the Casper Formation (Pennsylvanian) lies 30 miles to the west in the Shirley Basin. This mineral provides a source for attractive specimens. Attractive agates and agatized breccias located within the Hartville uplift 30-40 miles to the northeast, provide a lapidary source to collectors in the region (Hausel, 2014; Hausel and Sutherland 2000). In addition, the author discovered several hundred cryptovolcanic structures in this region, many have characteristics similar to kimberlite pipes.

The region surrounding the Palmer Canyon deposit is relatively unexplored. Nearby pelitic schist and vermiculite with similar geology to the Palmer Canyon occurrence, remain unexplored.

Geology

Palmer Canyon is located within the Wyoming craton in an area mapped as undifferentiated Archean granite-gneiss (Graff and others, 1982). This craton was established by 2.7 billion years (Eggler and others, 1988).

Quartzofeldspathic gneiss, granite gneiss, pelitic schist, and biotite-chlorite-vermiculite schist all occur within the Palmer Canyon deposit. Although there is no evidence that this deposit had ever been investigated for gemstones in the past, a small segment of the schist was briefly investigated for vermiculite prior to 1944. According to Hagner (1944), this occurrence, known as the Rolf prospect, was found in a N80°W trending, 65°SW dipping, biotite schist, which locally contained chlorite, kyanite, and corundum. The deposit was interpreted to have formed by the replacement of biotite by vermiculite under the influence of pegmatitic fluids (Hagner, 1944). Cordierite was not mentioned, and no physical descriptions of the corundum were provided by Hagner.

During field investigation in 1995, only one small prospect pit, about 3 feet deep and 3-4 feet across was found. Even though some samples of vermiculite-chlorite-biotite-corundum schist were found in the pit with as much as 20 percent corundum, there appears to have been no investigation into the potential for gemstones. Vermiculite was sought in the 1930s and 1940s as fire-resistant insulation. Following this investigation, the author discovered about 30% of vermiculite deposits in Wyoming contain ruby and sapphire showing a positive connection of these gemstones with the alumina rich rock. Vermiculite was never commercially mined from the deposit
Gneiss outcrop at Palmer Canyon

Thus, as a gem-prospector, you should get to know this rock type thoroughly (take some samples if you visit this spot), as there is good evidence that vermiculite is a highly aluminous altered rock that provides favorable conditions for a number of aluminum rich gemstones including ruby and sapphire. After you learn about this rock type, search Wyoming, Colorado, and Montana for vermiculites. Several vermiculites in the world are sources for ruby and sapphire!

 Mineralogy
Based on field reconnaissance, XRD (x-ray) analysis, and microscopic studies the Palmer Canyon deposit hosts five types of gemstones and near-gems. These include: (1) violet to blue, transparent cordierite (iolite), (2) dark-gray transparent cordierite, (3) reddish transparent to translucent corundum (dark pink sapphire), (4) white to light pink translucent corundum (sapphire), and (5) white to pink translucent to opaque corundum. In addition, low quality, dark gray, translucent to cloudy cordierite is also present, as is some corundum with well-developed rhombohedral parting that tends to crumble. These have little value as gems.

Cordierite (Mg, Fe)2Al4Si5O18, crystallizes in the orthorhombic (pseudohexagonal) crystal system. It typically forms short prismatic crystals with rectangular cross-sections but often exhibits elliptical to rounded morphology due to alteration or resorption caused by disequilibrium conditions at depth. The mineral is brittle, has conchoidal fracture, and may have poor cleavage parallel to b{010} and parting parallel to c{001}. It ranges in hardness from 7 to 7.5 and has a specific gravity of 2.55 to 2.75.


 According to Sinkankas (1964), the gemological term for cordierite is iolite. The word iolite is derived from the Greek word ion, meaning violet, is the common color of gem-quality cordierite. The color of cordierite may vary from yellow to green to blue to violet, but only the transparent blue and violet-blue grains are prized for faceting.

 Cordierite is often referred to as dichroite due to its strong pleochroism, which produces gemstones that appear to change shades of color depending on the angle it is viewed. In one direction, the iolite will appear sapphire-blue; when rotated, it will appear to be light grayish-blue to gray.

Corundum, Al2O3, typically occurs as tablet- or barrel-shaped, hexagonal prisms with basal terminations. The basal terminations often have distinct regular, triangular, striations, which are an expression of rhombohedral parting. The basal terminations themselves, are expressions of basal parting.

Gem ruby from Palmer Canyon, Wyoming (12 carats faceted gem).
Corundum with a hardness of 9, is second only to diamond in hardness. It has relatively high specific gravity (3.94 to 4.08) which results in detrital corundum sometimes being found concentrated in placer deposits with other minerals of high specific gravity such as gold, magnetite and garnet.

Most natural corundum is of industrial quality, but transparent to translucent varieties with their adamantine to vitreous luster, potentially yield gemstones known as ruby and sapphire. Red gem-quality corundum is known as ruby; all other colors of gem corundum are referred to as sapphire with a prefix denoting the color of the stone (Hurlbut and Switzer 1979).

The most desirable color of ruby is dark, purplish-red, known as pigeon's blood ruby. The most desirable color for sapphire is velvety cornflower blue called Kashmir blue. Some rubies and sapphires may exhibit asterism. Such stones exhibit six-rayed stars of light produced from light reflecting off oriented, needle-like, mineral inclusions of rutile within the corundum (Hurlbut and Switzer 1979). The needle-like crystals lie in planes perpendicular to the c-axis of the corundum.

Vermiculite schist filled with pink sapphires and blue kyanite
from Palmer Canyon, Wyoming
Corundum may occur as an accessory mineral in some metamorphic rocks such as mica schist, gneiss, and crystalline limestone. It may also occur as a secondary mineral associated with contact metamorphism of limestone. It has also been found in silica-poor igneous rocks such as syenite, nepheline syenite, serpentinite, and lamprophyre (Hurlbut 1966; Bauer 1968; Hausel 1996). In Wyoming, corundum has been found in gneiss, pelitic schist, and vermiculite schist.


Wyoming Occurrences

Cordierite Other than the Palmer Canyon occurrence, no other sources of gem-quality material are known in the state. However, Sinkankas (1964) mentions a massive cordierite deposit with gems capable of being cut found in Wyoming. Unfortunately, no location and no other information were given, and no records of this occurrence exist. Communication with John Sinkankas in 1995 indicated that he could not remember where this deposit was.

Mineralized terrains and mining districts of Wyoming (after Hausel).
Cordierite has been described in the South Pass greenstone belt of the Wind River Mountains in western Wyoming (Hausel 1991), and has also been identified in the Copper Mountain supracrustal belt of the Owl Creek Mountains in northwestern Wyoming (Hausel, Graff, and Albert 1985). Cordierite in these two metamorphic belts forms opaque, black to brown, rounded porphyroblasts typically less than 0.5 inch across. Many of the grains are partially to entirely replaced by fine-grained sericite and quartz.

Cordierite was also described to occur as almond-shaped masses in schist within the Sierra Madre southwest of Encampment, in southeastern Wyoming. The mineral is also described in baked shales and clays above burned coal beds in the Powder River Basin in northeastern Wyoming (Osterwald and others, 1966).

The largest occurrence of cordierite in the state (as well as the world) may possibly occur in the Laramie anorthosite-syenite complex in the central Laramie Range south of Palmer Canyon and Grizzly Creek according to early reports on cordierite. Osterwald and others (1966) described widespread, lenticular to tabular layers of cordierite in metanorite, syenite, and syenite-diorite gneiss along the northern margin of the complex. Some of the metanorite was reported to contain as much as 50-80% cordierite. The early reports indicated that this deposit (based on trenching and surface sampling) contained approximately 500,000 tons of cordierite!!! What does this mean?

One carat weighs only 0.2 grams and one ton has 4,536,000 carats! Thus if we were to assume this deposit was nothing but gem material, this would equal 2,268,000,000,000 carats (2.268 trillion carats)!

Of course, we do not know how much of this deposit is gem quality, but even if it is a small percentage, this could be the largest colored gemstone deposit on earth if the early (pre-world war II) geological resource estimates are correct. But also realize that this resource was based only on surface samples and not on drilling, thus this cordierite resource could be many times this size if we were to drill it to a depth of say just 100 feet.

Unfortunately, the author (Hausel) was unable to do much investigation of this deposit other than to collect a few samples along the road between Laramie and Iron Mountain. Here, all samples of cordierite were in the range of 1 to 4 carats and all were flawless gemstones.

Group of 8 to 12 carat iolites faceted from Palmer Canyon cordierites
Samples from the Vic Norris collection.
Elsewhere in the Laramie Range, cordierite has been reported in the Grizzly Creek area a few miles southwest of the Palmer Canyon.
Corundum Corundum has been reported at a number of locations in Wyoming. In addition to the Palmer Canyon deposit, corundum has been reported elsewhere in the Laramie Range, in the Granite Mountains, the Medicine Bow Mountains, Green Mountain, Wind River Mountains, and in the Sierra Madre. Reports of gem-quality corundum are rare in Wyoming although both ruby and sapphire have been reported (Hausel and Sutherland 2000).
Within the Granite Mountains of central Wyoming, are several reported corundum occurrences. One of these, the Red Dwarf deposit, lies northwest of Jeffrey City. The deposit was mapped by the author in 1995, and consists of corundum-bearing quartzofeldspathic gneiss with a strike length of 4,000 feet and widths varying from 20 to 50 feet. The gneiss grades from gray quartzofeldspathic gneiss along its northern end, to chloritic schist along its southern extent. It contains 1-10 percent corundum porphyroblasts partially to completely replaced by fuchsite. The fuchsite typically forms reaction rims encasing the corundum, or may occur as pseudomorphs after corundum. The largest known specimens of Wyoming corundum have been found here. These include red corundum, collected by the author, that was the size of a hen's egg, measuring more than 2 inches across. Another large specimen collected by J. David Love of the US Geological Survey; a fuchsite pseudomorph after corundum (with some preserved purplish-red corundum), measured more than 5 inches in length and 3 inches across.
A few specimens from the Red Dwarf have recently been cut into cabochons, but none have yet been faceted (Robert Odell, pers. com. 1998). These are purplish-red, translucent and cloudy. In addition to the corundum gneiss, a serpentinite found a short distance to the west, contains small (millimeter size), light blue, translucent to opaque corundum (Robert Odell, pers. com 1998). Locally, this rock contains as much as 20 percent corundum (Hausel and Sutherland 2000).

Deep- to purplish-red rubies were described near Sweetwater Divide in central Wyoming. Specimens of this material were cut and polished producing some star-rubies (Curtis 1943) (author’s note: this may be the Red Dwarf corundum deposit located northwest of Jeffrey City in central Wyoming).
Further west, pale-blue and white sapphires are found in mica schist enclosed by gray-brown granite near Sweetwater Station. This deposit, known as the Abernathy prospect, contains abundant 1-inch diameter nodular ‘sapphires’. But for the most part, these are badly shattered and altered around the edges (Love 1970). Pale to bright-red rubies were found in mica schist north of the Abernathy deposit at the Marion prospect. Some of these were cut into gems (Osterwald et al 1966).

Other rubies have been found in float in the Granite Mountains. According to Love (1970), soft green mica schist boulders with dark red rubies were found near Muskrat Creek in the Wind River Formation (Eocene) near Beaver Rim, west of the Gas Hills uranium district, about 12 miles north of the Red Dwarf deposit. These rubies were up to 1 inch in diameter and highly fractured. The source of the schist was not determined. A nearby placer was also reported to contain abundant, bright red (>1 inch in diameter), fractured rubies (Osterwald et al 1966). Chloritic schist float, similar to the Red Dwarf schist, was also found in the Crooks Gap Conglomerate (Tertiary), along the northern flank of Green Mountain, about 15 miles to the southeast of the Red Dwarf (Avon Brock, pers. com 1982; Hausel 1986).

Three flawless iolite gemstones sit on a iolite gneiss from Palmer Canyon. The largest gem weighed more than 0.5 carat

Some corundum was also discovered in the Platt River valley along the edge of the Medicine Bow and Sierra Madre Mountains in southeastern Wyoming. One of these occurs at Baggot's Rock, where specks of corundum are found with kyanite and vermiculite in biotite- and hornblende-schist (Osterwald et al 1966). The deposit was mined for vermiculite from 1937 to 1941 (Hagner 1944).
A few miles south, an open cut in vermiculite hosted by granite-gneiss in the Homestead Draw area, exposed scattered pockets of ruby. Some of these have reaction rims of fuchsite similar to those at the Red Dwarf ruby deposit. Rubies are also reported in another vermiculite to the southwest (Ralph Platt, pers. com 1998).

Abundant industrial corundum with some rubies (including star rubies), are reported in the Big Sandy drainage in the southern Wind River Mountains in western Wyoming (Spendlove 1989). The source of this corundum has not been identified.

Few in situ corundum deposits are known in the Laramie Range of southeastern Wyoming. Even so, some detrital corundum was identified in panned sample concentrates collected in a few drainages during exploration for diamonds in the 1980s (Hausel, Sutherland, and Gregory 1988). There is also a report of purple corundum (0.75 inch in diameter and 4 inches in length) that was found in a granite xenolith in Elk Park a few miles northwest of Palmer Canyon (Ray Harris, pers. com 1992).

Palmer Canyon Deposit
Cordierite was initially discovered in samples collected in Palmer Canyon in 1995, during reconnaissance of corundum-bearing schist. The cordierite was found in quartzofeldspathic gneiss a short distance east of the Roff vermiculite prospect pit, and was later confirmed by XRD analysis (Robert Gregory, pers. com 1996).

The cordierite gneiss crops out over 200 feet, with a width of about 10 feet. The gneiss disappears under soil in every direction from the outcrop, and thus may be more extensive. The presence of detrital cordierite found in soil 300 feet up-slope from the outcrop, suggests that the deposit may have a minimum strike length of 500 feet.

Several samples of cordierite gneiss were collected from the property during initial field investigations. These include transparent cordierite grains that weighed 1.5, 6, 11.5, 13.5, 14, 63.5, 109.5, 308.5, 887, 1,715 and 2,948 carats. Samples collected more recently include a large nodule of facet-grade, violet to blue, massive, transparent cordierite that measured 4.25 x 2.5 x 1.25 inches (>3,000 carats), which is the largest cordierite found in Wyoming, to date. The specimen has several fractures restricting the size of stones that can be cut from the nodule. Some of the gneiss collected from the property contains as much as 20 percent transparent cordierite.

Gem cabochons of kyanite from Palmer Canyon.
Much of the cordierite occurs as rounded to disseminated grains, or as large nodules. A few nodules are inter grown with quartz. In most cases, the strong foliation of the host rock parallels the margins of the nodules, but in a few, the foliation expressed by mica is seen to terminate against one edge of the nodule (i.e., biotite grains are oriented perpendicular to the edge of one surface of the nodule).

The host cordierite gneiss is dark gray to gray cordierite-biotite-sericite-quartz gneiss. Kyanite and sillimanite may also be present, but occur as a minor component of the gneiss. Some secondary calcite may occur as crusts on some surfaces, and many of the cordierite nodules exhibit a very thin (millimeter) zone of alteration along the edge of the nodule that consists of chlorite and sericite.

Three varieties of cordierite were noted. These include: (1) transparent to translucent, violet to blue cordierite with poorly developed parting and cleavage; (2) dark-gray transparent to translucent cordierite with distinct parting and cleavage; and (3) dark-gray, cloudy, translucent to opaque cordierite with common mineral inclusions and distinct parting and cleavage. In the samples collected by the author, variety 1 dominates.


Many specimens of variety 1 appear to be suitable for faceting. This material ranges from a pleasing violet to a very light-blue color and exhibits only a hint of cleavage and parting. A few specimens of variety 1 cordierite were faceted and loaned to the author by Vic Norris. These produced iolite gems with excellent transparency and pleochroism that weighed 0.5, 1.0 and 1.49 carats. Microscopic examination of the 0.5 carat iolite triangular brilliant showed a tiny biotite inclusion that is not visible to the naked eye. The 1.0 carat stone was fashioned into a marquise, and shows several tiny unidentified mineral inclusions under the microscope that are not readily visible to the naked eye. The largest of the three iolites was cut into a modified scissors cut. This stone is clear, but unfortunately has a visible fracture.
Three iolite gems fashioned from 
Palmer Canyon cordierite sit next to 
nodular, transparent cordierite. The 
box containing the iolite gems
 is 0.9 inch across. The nodular iolite
(Palmer Canyon star) was the largest
 iolite gemstone in the world at time of 
its discovery and weighed 1,750 carats.
Later, this stone was dwarfed by the 
Grizzly Creek Blue Giant found by the
 author a few years later in Grizzly 
Creek, which weighed 24, 150 carats.
Even so, samples of massive iolite in 
the outcrop are estimated to weigh 
much greater than 100,000 carats!

Some gray to dark gray cordierite (variety 2) also exhibits excellent transparency. Unfortunately, this variety has well-developed parting parallel to c{001} and cleavage along b{010} limiting the size of facetable material. Many of the gray specimens also exhibit good rectangular cross sections, and a few exhibit pseudohexagonal habit.

Variety 3 cordierite is not suitable for gems as the faceted material has many flaws. Two samples of variety 3 cordierite were faceted. The larger stone weighs 3.9 carats and was faceted into a lozenge-cut stone. The 3.4-carat cordierite was cut with a marquise crown and a step-cut pavilion. Unfortunately, both stones are extensively flawed with fractures, visible cleavage, and some visible mineral inclusions.


Faceted (variety 3) iolite from Palmer
Canyon has too many flaws to produce
good high-quality gems. Next to the
faceted stones are samples of variety 2
rough with well-developed cleavage &
parting (photo by the author).

Corundum. The corundum at Palmer Canyon was also investigated by the author. During the initial investigation, several rock specimens were collected within the old Rolf vermiculite pit, as well as nearby outcrops, and many of these contained some corundum. The corundum is locally abundant, and a few samples contain 15–20 percent corundum.


The schist was traced for nearly 1,000 feet along strike. Samples examined under a binocular microscope show that the corundum-chlorite-biotite schist also contains trace sillimanite and uncommon kyanite. Some spectacular foliated kyanite-mica-schist located adjacent to the corundum schist, exhibits abundant 1– 2-inch-long blades of kyanite. Some of this schist also contains trace corundum.

Some corundum is translucent to transparent, white, pink and less commonly, red. The corundum occurs as porphyroblasts in the schist and forms hexagonal prisms and platelets. The largest specimen collected from the deposit by the author at the time of discovery was 1-inch-long prism with a 0.3-inch diameter. Another broken corundum measured 0.4 inch in diameter. Much of the corundum from this deposit appears to average about 0.2 inch in diameter.

Dark-pink sapphire gem with brownish-
pink sapphire cabochon sit on 
corundum schist from the Palmer 
Canyon deposit (photo by the 
author).

Microscopic examination of the corundum shows the presence of both red ruby and pink to white sapphire. Much of the corundum is transparent to translucent, and only one opaque white to pink corundum was seen in the samples collected during this study.

Two specimens of the corundum were recently fashioned into cut stones. One is a brownish-pink, opaque corundum that was fashioned into a 1.4-carat cabochon. The specimen is pleasing to the eye, but is a near gem of low value. A specimen of dark-pink corundum was also faceted into a transparent, 1.1-carat marquise. This stone exhibits a few minor flaws visible to the naked eye, but otherwise is an attractive gem that was appraised for $300. Three other sapphires were faceted producing gemstones weighing 0.75, 2, and 3 carats (Vic Norris, pers. com 2002).

Fashioned corundum from the Palmer
Canyon deposits surrounded by iolite.
The brownish pink cabochon is translucent
to opaque, while the dark pink marquise
is an attractive transparent gem with
minor flaws (photo by the author).

Conclusions

Until recently, few people considered Wyoming to have potential for gemstones other than nephrite jade. However, during the past few decades, many gemstones were discovered by various prospectors and the author in Wyoming showing that the state to be the most diversified state in the US for variety of gemstones. The variety of gemstones identified by the author include iolite, kyanite, ruby, sapphire, apatite, peridot, pyrope garnet (cape ruby), almandine garnet, spessartine garnet, chrome enstatite, chrome diopside (cape emerald), fire opal, gem opal, onyx, agate, and jasper. Other gemstones discovered since 1975 by other researchers include diamonds, other forms of agate, varisite and common opal.

The possibility of similar deposits to the Palmer Canyon occurrence needs to be addressed, as much of Wyoming’s exposed mountain ranges are cored by amphibolite-grade schists and gneisses. These include large blocks of terrain with metapelites. Some are located only a few miles from the Palmer Canyon occurrence.

Recent field investigations by the author have suggested a possible correlation between corundum and vermiculite: about 10-20 percent of the vermiculite deposits investigated to date, contain some corundum. Thus further investigations of Wyoming’s vermiculite deposits may lead to the discovery of other corundum occurrences. In summary, the presence of additional occurrences of gem-quality corundum and cordierite in Wyoming needs to be seriously considered.

So, how come no mines have yet been developed on these deposits? It is often said in the mining industry that "mines are not found, they are made". What this refers to is that, yes, a commercial deposit must first be discovered, but this doesn't guarantee anything. After a commercial deposit is found, there are land and water ownerships and rights, too many construction, mining, environmental and discharge permits; raising of $tens of millions in capital (sometimes as much as $1.5 billion), infrastructures to be built, designing a mine and mill, finding workers with the right kind of expertise, attorneys, marketing, and the list goes on and on. The chances of making a mine out of a discoveries are very, very slim. It just takes the right group of people, the right time in history, and the proper alignment of stars so to speak.

Few people know this better than three Wyoming geologists - Mark Bronston, Dr. Paul Graff and W. Dan Hausel. These there (along with four other geologists) were awarded the highest honor in economic geology by the Canadian PDAC for finding one of the largest gold deposits in history. In 1988 and 1989, seven geologists made an incredible discovery in 1988 and 1989 at Donlin Creek and Snow Gulch Alaska after much detailed geological detective work. They discovered a 5 to 6 mile long gold deposit with widths of more than 100 feet. The deposit is now considered as one of the 10 greatest gold discoveries in history! Surface sampling and drilling to date suggest this one deposit contains a minimum of 180 million ounces of gold! To get an idea of how much this is worth, just multiply 180 million by the current gold price. Then keep in mind that this deposit still has nearly three miles of mineralized trend that remains to be drilled out. And once mining begins, more gold will likely be found.

The Northern Miner described this as a MONSTER gold deposit. It is so large that this one deposit has more than 450 times the amount of gold mined during the entire history of Wyoming. It has more than 10 times the amount of gold mined during the entire mining history of the famous Klondike, and it has more gold than mined throughout the rest of Alaska!

So, with a gold deposit worth more than $180 billion in gold, one would think since it was discovered by these seven WestGold geologists in 1988 and 1989, that the deposit would be producing, particularly since WestGold was owned by DeBeers and Anglo American - two mining giants. Nope! The mine and infrastructure are still under construction after all of these years, and WestGold, DeBeers, and Anglo American no longer have any holdings in the property.  So, here is is, nearly 30 years later, and one of the richest deposits ever to be found is still not a mine.

References


  • Bauer, M. 1968. Precious stones. New York: Dover Publications. 627 p.
  • Curtis, L. B. 1943. Letter to H. D. Thomas, February 21, 1943. Wyoming State Geological Survey unpublished files.
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      The Gemhunter, a polymath of rocks, martial arts, stars, pencil, written word & public speaking. A Hall of Fame Martial Artist, Geologist, Author and Public Speaker. Look for numerous blogs by the GemHunter on gemstones, gold and martial arts designed to help the reader learn about these subjects.